Mesoscopic perspectives on dynamic van der Waals theory for liquid–vapor phase transition

Abstract

We present a macroscopic dynamic van der Waals theory for liquid–vapor phase transition from mesoscopic perspectives offered by the kinetic model for multiphase fluids. We show that the excess effects stem from the unbalanced long-range molecular interaction in the inhomogeneous region, and, thus, only the excess internal (potential) energy but not the excess entropy is introduced. The excess internal energy is given as −12κρ∇·∇ρ rather than the canonical 12κ∇ρ·∇ρ, which leads to the same equilibrium state but different thermohydrodynamics. The present dynamic equations are identical to the macroscopic equations recovered by the kinetic model.